Exponential Moving Average (EMA)

The Exponential Moving Average (EMA) addresses the simple moving average's main flaw: its lag. Where the SMA gives every candle in the period the same weight, the EMA weights the most recent ones more heavily. It therefore reacts faster to reversals, while keeping the smoothing effect that makes moving averages useful.

This responsiveness makes it a staple of short- and medium-term strategies. It is also at the heart of the MACD, which is built entirely on the difference between two EMAs.

How it's calculated

The EMA is computed recursively: each new value combines the current candle's close with the previous EMA, using a smoothing coefficient that depends on the period. The shorter the period, the more weight this coefficient gives to the latest close. In practice, a recent candle weighs heavily in the result, and the influence of older candles decays gradually without ever fully disappearing : hence the name "exponential".

In Screener.Trading, the EMA's default period is 20 candles, adjustable in each rule. Common periods are 9 and 21 for the short term, 50 for the medium term and 200 for the underlying trend.

How to read it

• Trend: as with the SMA, the EMA's slope and price's position relative to it indicate the market's direction on its horizon.
• EMA crossovers: a short EMA (e.g. 9) crossing above a longer one (e.g. 21) signals bullish acceleration; the reverse cross, fading momentum.
• Dynamic support: in a clear trend, price often bounces off its 21 or 50 EMA during pullbacks.

The flip side of responsiveness is noise sensitivity: a short EMA tracks price so closely that it generates constant crossovers in a hesitant market. Responsiveness and reliability trade off against each other : the fundamental compromise of all moving averages, which the EMA shifts but does not eliminate.

In the screener

Rule examples you can build in Screener.Trading: "9 EMA above the 21 EMA on H4" to filter assets with bullish momentum; "close above the 200 EMA on D1" as an underlying trend filter; "close below the 21 EMA on H1" to detect a potential pullback. You can also compare an EMA against an SMA of the same period to gauge the recent acceleration of price.

Cross-timeframe comparisons let you combine horizons: for example, keep only assets whose H1 close is above the daily 200 EMA, then look for a short EMA crossover intraday. Candle offsets also let you target fresh crosses: "the crossover happened at most 3 candles ago".